1. Field of the Invention
The invention relates generally to adjustable bicycle seat posts and, more particularly, to a telescopic seat post that allows a bicycle seat to be adjusted while the bicycle is being ridden.
2. Related Art
For those engaged in competitive cycling, such as the sport of mountain biking for example, it is sometimes advantageous to adjust the position of the body while riding in order to optimize the control and power over the bike. For instance, when descending a steep hill, a rider sometimes will drop back behind the bicycle seat in order to lower the body position and thereby gain more control over the bike. At most other times, such as on flat terrain, it is most advantageous for the rider's body to be positioned high for maximum leg extension in order to achieve optimum pedal power.
Another challenge faced by competitive mountain bikers is that the various components of the bike are subjected to exposure to water, mud, dirt, and other debris which can quickly impair the proper operation of various moving parts. These agents are compounded by the extreme stresses imposed on bicycle components during competitive use.
In many bike riding situations, but especially in competitive cross-country events, lowering a rider's center of gravity for steep descents and then returning to a raised, pedal stroke condition is extremely important for handling, speed, and safety. In cross-country riding applications in particular, many riders position their seats in a permanent position much higher than do riders of free-style or even downhill racing. This is done because a higher seat position allows for well-developed pedal strokes needed to sustain power to the pedals. Some other cross-country riders will fix their seat in a permanent position below an optimal pedal power position as a compromise between climbing and descending advantages.
Various adjustable-height bicycle seat posts have been proposed which enable a user to vary the height of the seat between two or more positions while riding. The posts are typically in the form of a telescoping tube structure mounted at its lower end to the bicycle frame and which carries a seat at its upper end. Some form of a locking or clamping mechanism is provided which selectively locks the tubes in one of two or more positions. In some cases, a spring is provided which acts to constantly bias the seat toward an extended, or raised, condition.
Most prior art adjustable-height bicycle seat post constructions operate on the principle of inserting a latch pin through aligned holes in the telescoping tube structures. The latch pin is actuated by deploying or throwing some kind of actuator. Sometimes, the actuator is a simple pull knob connected directly to the latch pin, and in other situations, the actuator may be a thumb switch or other control device located remotely from the latch pin and connected through a flexible motion transmitting cable. When a rider is seated on the bicycle seat, his or her body weight creates a large shearing force between the telescoping tube structures. This shearing force is resisted by the latch pin.
When the bicycle rider desires to adjust the position of the seat, he or she actuates the mechanism to withdraw the latch pin from the aligned holes in the telescoping tubes and simultaneously lifts his or her body weight off of the seat in order to decrease the shearing force and allow the latch pin to be extracted from the aligned holes. The timing of this maneuver is critical. If the rider's weight is not lifted at the same time as the latch pin is being extracted from the holes, the latch pin will become trapped in position. This can distract the rider and potentially break the actuator, cable mechanism, or other components in the latch mechanism. Accordingly, riders which user a prior art style seat adjustment mechanism must precisely time deployment of the actuator together with the step of lifting their body weight off of the seat. As will be appreciated, in competitive racing or difficult terrain situations, this methodically timed sequence of events is an unwelcome distraction.
Accordingly, there is a need for an improved adjustable bicycle seat post assembly which does not require the bicycle rider to precisely time deployment of an actuator together with the change in seat height.